G 1500 1/2 Ton Van V6-4.3L VIN W (1997)
Manifold Pressure/Vacuum Sensor: Description and Operation
Manifold Absolute Pressure (MAP) Sensor
PURPOSE
The Manifold Absolute Pressure (MAP) sensor responds to changes in the intake manifold pressure. The pressure changes as a result of engine load and
speed. The map sensor converts this to a voltage output.
OPERATION
A closed throttle on engine coast down would produce a relatively low MAP output voltage. A wide open throttle would produce a high MAP output
voltage. This high output voltage is produced because the pressure inside the manifold is the same as outside the manifold. The MAP is inversely
proportional to what is measured on a vacuum gage. The MAP sensor is used for the following:
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Altitude determination.
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Ignition timing control.
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Exhaust Gas Recirculation (EGR) diagnostic.
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Speed density fuel management default.
